1. Field of the Invention
The embodiments of the invention generally relate to fuse state detection, and particularly, to a circuit for detecting whether or not a fuse is blown.
2. Description of the Related Art
Recently, simple electrical fuses that can be blown on demand have been designed into chips to alter chip performance after fabrication. For example, fuses within chips can be used to help repair flaws, to manage power consumption or to control individual circuit speed. Similarly, fuses within chips can be blown in order to optimize or tailor chip performance and capability based on customer demands. These fuses are typically thin strips of conductive material (e.g., semiconductor or metal) that are incorporated into a conductive path within a circuit. Such fuses can be blown (i.e., made less conductive) by forcing an excessive current there-through.
Chips that are designed with these fuses are also designed with fuse state detections circuits (i.e., fuse sense circuits) for determining whether or not individual fuses have been blown. Various techniques for detecting fuse states are known, as illustrated in U.S. Patent Application Publication No. US2005/0151578 of Huang et al., published on Jul. 14, 2005 and incorporated herein by reference. These techniques generally detect the change in the resistance of the fuse device from a low value to a high value. For example, one type of fuse state detection circuit (i.e., a single-sided fuse state detection circuit) compares the voltage of a current that has passed through the fuse to a reference voltage. Another type of fuse state detection circuit (i.e., a differential fuse state detection circuit) compares the voltage of a current that has passed through the fuse with the voltage of current that has passed through an identical reference fuse. Such known fuse detections circuits offer advantages and disadvantages that are related to both flexibility and sensitivity. These advantages and disadvantages must be balanced when determining which fuse detection circuit to use. Therefore, there is a need in the art for an improved fuse detection circuit that provides the same or greater advantages with regard to flexibility and sensitivity as both single-sided fuse detection circuits and differential fuse detection circuits.